Z94.16 - Quality Assurance & Reliability

OBSERVED VALUE. The value of a characteristic obtained as the result of a single observation. [1: 2.6].

ONE-SIDED TEST. A test in which the statistic used is one-dimensional and the critical region is the set of values less than a critical value (or the set of values greater than a critical value). [1:2.73]

OPERATING CHARACTERISTIC CURVE (OC CURVE). (1) Type A: A curve showing, for a given sampling plan, the probability that an acceptability criterion is satisfied as a function of the lot quality level. (2) Type B: A curve showing, for a given sampling plan, the probability of accepting a lot, as a function of the quality level of the process from which the lots come; as used for some types of plans, a curve showing the percentage of lots, or product items, that may be expected to be accepted as a function of the process quality level. (3) Type C: A curve showing, for a continuous sampling plan, the long-run percentage of product accepted during the sampling phase as a function of the quality level of the process.[ 2.6.1]

ORDER STATISTIC. When the observations in a sample are arranged in non-decreasing order of magnitude, each of these ordered observations is a value of a random variable, known as an order statistic. More generally, any statistic based on order statistics in this narrower sense is also called an order statistic. Example: The kth value in the non-decreasing sequence of observations x[k] is the value of the random variable X[k] called the "kth order statistic". In a sample of size n, the smallest observation x[1] and the largest observation x[n] are the values of the random variables X[1] and X[n], the first and nth order statistic, respectively. The range, x[n] - x[1], is the value of the order statistic X[n] - X[1]. [2: 2.46].

OUTLIERS. Observations in a sample, so far separated in value from the remainder as to suggest that they may be from a different population, or the result of an error in measurement. [1: 2.64]